Fat-tailed Mouse Opossum Thylamys

Introduction

Meet Thylamys, the fat-tailed mouse opossum from South America!

Thylamys pallidor

Thylamys pallidor

We collected body measurements of 73 individuals from four species of Thylamys in NHM Mammal collection and analysed the results…

1. Which species is the cutest longest?

## Analysis of Variance Table
## 
## Response: Total_length
##           Df Sum Sq Mean Sq F value    Pr(>F)    
## Species    3  55763 18587.6  35.052 9.699e-14 ***
## Residuals 67  35529   530.3                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Call:
## lm(formula = Total_length ~ Species, data = marsupial)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -52.714 -11.739   2.235  15.500  53.714 
## 
## Coefficients:
##                  Estimate Std. Error t value Pr(>|t|)    
## (Intercept)       238.000      5.757  41.341  < 2e-16 ***
## Specieskarimii    -83.286     10.435  -7.981  2.6e-11 ***
## Speciespallidior  -48.235      6.981  -6.909  2.2e-09 ***
## Speciesvenustus    -2.714      8.427  -0.322    0.748    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 23.03 on 67 degrees of freedom
##   (2 observations deleted due to missingness)
## Multiple R-squared:  0.6108, Adjusted R-squared:  0.5934 
## F-statistic: 35.05 on 3 and 67 DF,  p-value: 9.699e-14

2. Does altitude affect size?

## Analysis of Variance Table
## 
## Response: Altitude
##              Df    Sum Sq Mean Sq F value Pr(>F)
## Total_length  1   1355460 1355460  0.7971 0.3753
## Residuals    64 108827710 1700433
## 
## Call:
## lm(formula = Altitude ~ Total_length, data = marsupial)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1587.1  -995.6  -817.0   811.4  2689.7 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)   
## (Intercept)  2521.018    918.878   2.744  0.00788 **
## Total_length   -3.926      4.398  -0.893  0.37530   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 1304 on 64 degrees of freedom
##   (7 observations deleted due to missingness)
## Multiple R-squared:  0.0123, Adjusted R-squared:  -0.003131 
## F-statistic: 0.7971 on 1 and 64 DF,  p-value: 0.3753

3. Is there a relationship between the length of hind foot and body?

## Analysis of Variance Table
## 
## Response: Hind_foot
##                   Df  Sum Sq Mean Sq F value    Pr(>F)    
## Head_body          1 118.627 118.627 70.7803 6.775e-12 ***
## Species            3  50.922  16.974 10.1278 1.556e-05 ***
## Head_body:Species  3   8.642   2.881  1.7187    0.1722    
## Residuals         63 105.588   1.676                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Call:
## lm(formula = Hind_foot ~ Head_body * Species, data = marsupial)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -4.4653 -0.6587 -0.0086  0.7369  5.0076 
## 
## Coefficients:
##                            Estimate Std. Error t value Pr(>|t|)   
## (Intercept)                 7.68237    2.44989   3.136  0.00260 **
## Head_body                   0.06756    0.02066   3.271  0.00174 **
## Specieskarimii              0.53827    3.16268   0.170  0.86540   
## Speciespallidior            0.23726    3.39545   0.070  0.94451   
## Speciesvenustus             6.53074    3.17774   2.055  0.04402 * 
## Head_body:Specieskarimii   -0.03329    0.02995  -1.111  0.27061   
## Head_body:Speciespallidior -0.01213    0.03303  -0.367  0.71459   
## Head_body:Speciesvenustus  -0.05891    0.02748  -2.144  0.03593 * 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 1.295 on 63 degrees of freedom
##   (2 observations deleted due to missingness)
## Multiple R-squared:  0.6279, Adjusted R-squared:  0.5866 
## F-statistic: 15.19 on 7 and 63 DF,  p-value: 1.872e-11

4. Do males and females differ in size?

Sample size = 37 males, 36 females.

Conclusions

We acknowlegde the significiant limiations of our research, but onwards and upwards to greater data sampling!

(Not a mouse opossum, but equally cute)

(Not a mouse opossum, but equally cute)